Yes, it is possible to move an elastic IP address across accounts. All you have to do is provide AWS with the IP address, the current account number, and the target account. They also need written confirmation from both AWS accounts confirming the transfer requests. This means that the source account has to log a case requesting them to move the IP address to the target account. The target account must also log a separate case requesting them to accept the new IP address which has been moved from the source account.